1. Technical Field
This invention relates to a color conversion filter panel, which is combined with an organic electroluminescent (EL) light-emitting panel to form a color organic EL display. More specifically, this invention relates to the structure of a separation partition wall that the color conversion filter panel comprises.
2. Background Information
One multicolor light emission method to obtain full-color or multicolor images in an organic EL display is a color conversion method in which light emitted by a light-emitting panel is absorbed, wavelength-converted into light at a wavelength different from the absorbed wavelength, and is emitted. In this method, a color conversion filter panel is positioned at the front face of the light-emitting panel.
A color conversion filter panel has a basic structure in which a color conversion layer including a color conversion dye is arranged on a transparent substrate. As a method of pattern formation on such a panel, Japanese Patent Application Laid-open No. H08-286033 discloses a method in which the color conversion layer is formed into a pattern by a photolithography method, using a material in which the color conversion dye is dispersed in photoresist or another polymer material. And, the method, disclosed in Japanese Patent Application Laid-open No. H02-216790, of forming a pattern by a method of evaporation deposition of the color conversion dye or another dry process is well known.
Further, the method, in Japanese Patent Application Laid-open No. 2000-122072, of using an inkjet method in pattern formation of a color conversion layer is well known.
Japanese Patent Application Laid-open No. 2000-353594 discloses, in light of the above methods, a method of providing separating partition walls between patterns of color conversion layers, to regulate the spread of ink drops dispensed by an inkjet method. Japanese Patent Application Laid-open No. 2007-095342 and similar disclose a method of regulating the ink wettability of materials used in the separating partition walls, and a method of making the cross-sectional shape of the separating partition walls an inverted trapezoid to control the thickness of the applied film to be uniform.
As stated above, when color conversion layers adjacent on a substrate and with different chromaticities are formed in patterns by an inkjet method, the provision of separating partition walls between patterns to prevent spreading of ink drops is a well-known technique. However, even if a simple separating partition wall is provided, color mixing of inks between adjacent color patterns due to the effects of the ink wettability of the separating partition wall material and the ink surface tension cannot be prevented.
Japanese Patent Application Laid-open No. 2004-111166 discloses a method, in a method of using an inkjet method to form organic light-emitting layers of different chromaticities in each of the subpixel regions divided into a matrix-like mesh by insulating partition walls between electrodes in order to enable multicolor emission of an organic EL light-emitting panel, of providing depressions and protrusions on the insulating partition walls, to prevent color mixing of inks between adjacent organic light-emitting layers.
When the above technique is employed to provide separating partition walls having depressions and protrusions on matrix-like mesh-shape partition walls on a transparent substrate, and an inkjet method is used to form color conversion layers between the separating partition wall meshes, color mixing of inks which pass over the separating partition walls can be prevented. However, when a color conversion filter panel obtained by this method and an organic EL light-emitting panel are joined together with a transparent resin layer interposed between the two panels to manufacture a photoemission-type organic EL display, the flow of transparent resin is obstructed by the matrix-like mesh-shape separating partition walls. As a result, uniform packing of the transparent resin in each of the meshes is extremely difficult, and numerous air bubbles remain between the two panels, causing unevenness in the image brightness.
When manufacturing a photoemission-type organic EL display by joining together a color conversion filter panel and an organic EL light-emitting panel with a transparent resin interposed between the two panels, by using a color conversion filter panel in which separating partition walls are arranged in stripe shapes on a transparent substrate, satisfactory flow of the transparent resin can be obtained, and the remaining of air bubbles between separating partition walls can be prevented. Further, by providing depressions and protrusions on the stripe-shape separating partition walls, applying the above-described technique, it is possible to prevent color mixing of adjacent inks for color conversion layer formation which pass over separating partition walls when using an inkjet method to form color conversion layers between separating partition walls.
When forming color conversion layers by an inkjet method utilizing separating partition walls arranged in stripe shapes, at the length-direction end portions of the separating partition walls, ink for color conversion layer formation leaks out to outside color conversion layer formation regions along the side walls of separating partition walls due to the wettability with the separating partition wall faces and similar, and leaks out into the tip portion regions of separating partition walls and/or adjacent color conversion layer formation regions, giving rise to color mixing between inks, as shown in FIG. 8. The leaking-out of ink along the side faces of the length-direction end portions of these separating partition walls reduces the effective screen region relative to the color conversion layer formation region. Further, in order to secure an effective screen region, it is necessary to anticipate the leaking-out of ink and secure a large frame region surrounding the screen region.